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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 9 November 2017 by dana1981

Last week news stories came out that said that global human carbon emissions may have peaked, essentially implying that we could already be over the hump and on the way to solving climate change—while other news stories that same day and in that same publication noted that atmospheric carbon dioxide concentrations jumped by a record amount in 2016. These stories exemplify the emotional roller coaster that often comes with following climate change news. How can we reconcile the ebbs and flows between hopeful and apocalyptic climate stories?

The answer lies in considering the timeframe around a piece of climate news. For example, the seeming contradiction in the two news reports is explained by the monsterEl Niño event of 2016 that intensified droughts and consequently weakened the ability of vegetation to absorb carbon dioxide—showing that while human carbon pollution is responsible for the long-term rise in atmospheric concentrations, there is still ample short-term natural variation.

To give a second example: In a recent story, the managing director of the International Monetary Fund was quoted saying: “If we don't do anything about climate change now, in 50 years' time we will be toasted, roasted and grilled.” While that is an alarming statement, it focuses on a potential scenario in which half-a-century from now we have failed to change the course of our climate policies.

It’s important to remember, however, that with the international Paris climate accords, nearly every nation in the world agreed to begin the process to alter that worst-case course.

Another recent story noted that there’s a large gap between the Paris climate goals and the emissions cuts we’ve achieved so far. But the agreement was signed a mere two years ago, and global carbon emissions appear close to peaking. (They must peak by around 2020 to give us a realistic chance to meet the Paris targets). Moreover, it was agreed that countries must strengthen their emissions pledges during five-year reviews to meet the Paris goals, which means it’s hardly fair to pass judgment at this date. True, it’s too early yet to know if the world’s nations will indeed be able to follow through with such ambitious plans, but there are positive signs. For example, China had pledged to achieve peak carbon emissions by 2030, but it appears to already be approaching that goal 10-to-15 years ahead of schedule. That’s a significant development, so it bears repeating: China may reach its carbon reduction goals 10-to-15 years ahead of schedule.

On the other hand, the climate news coming out of the United States under the Trump administration seems constantly grim. However, the United States is just one country, and even there we see some good long-term news. Despite the administration’s efforts to maximize coal burning and the associated carbon pollution, coal is rapidly being phased out of the American power grid for purely economic reasons; quite simply, wind, solar, and natural gas are cheaper options.

Ultimately, the wildly fluctuating tone in climate change news stems from the fact that we now stand at a critical point in human history. To avoid causing exceptionally damaging climate changes, we must take aggressive steps now to cut human carbon pollution, and those actions must continually accelerate in the coming decades. The future climate will depend on the path we choose now and in the foreseeable future. Today’s scientists and journalists are trying to read the tea leaves to determine which path we’re taking, which leads to a see-sawing between "there’s hope" and "we’re doomed" stories.

Comments

I think that part of the problem is that many people are not clear on the difference between carbon emissions and concentration of atmospheric CO2. I understand the difference but not how they are related.

The Keeling curve is currently rising at an accelerating rate. It has to stop rising and instead trend downwards to 350 ppm at least. But what would our emissions be doing while this change occurs?

I envisage five states of the Keeling curve:

(1) CO2 concentration rises at an accelerating rate

(2) CO2 concentration rises at a constant rate

(3) CO2 concentration rises but at a decreasing rate

(4) CO2 concentration stops rising and remains constant

(5) CO2 concentration starts decreasing

For each of these five states, what would our corresponding emissions be doing? Please enlighten me.

Anthropogenic carbon emissions are not the key value, it is total greenhouse gas emissions less natural reductions from all natural systems. The other most important number is the rate of increase of all greenhouse gases from feedback mechanisms. These two will determine how long we can survive. Too much emphasis is put on just our emissions. There are many huge natural sources waiting in the wings.

I agree that there are Feedback mechanisms to be concerned about. But all of those feedbacks are triggered by Anthropogenic emissions.

So the concern must remain focused on the rapid ending of Anthropogenic GHG impacts because of the potential for massive feedback magnification of those impacts (primarily the burning of fossil fuels, but also many other human actvities).

And, as metioned by Digby Scorgie@1, the obvious requirement is to get back down to a 350 ppm CO2 level. That will require human actions that remove GHG from the atmosphere in a truly lasting way (more Anthropogenic GHG impacts, but ones that reverse the tragic irresponsible developed history of impacts). Tragically, the reduction/reversal of the CO2 impacts in the oceans may be more difficult.

And the greatest tragedy is that the people who benefited most from creating the daunting challenges and damaging consequences now faced by humanity will not suffer any personal loss of enjoyment 'in their lifetime'. And that is the tragedy that really should be focused on.

(5) CO2 emissions are net negative, meaning it is actively being removed from the atmosphere faster than it can outgas from the ocean at atmospheric levels are dropping

We are currently somewhere between (1) and (2).

For those interested in getting more answer to tsuch questions, there is a Reddit AMA going on today (from AGU):

10 November, Dr. Sarah Doherty and Dr. Radley Horton, two authorsof the Climate Science Special Report(http://www.globalchange.gov/content/cssr), part of the National ClimateAssessment, are hosting a Reddit Ask Me Anything (AMA) from 1-3 pm EST as part of AGU’s AMA series. The recent Climate Science Special Reportfocused on climate change in the U.S. and Sarah and Radley will answerquestions on how our climate is changing, what causes it, and what toexpect in the years ahead. link

The graph in box 6.1 shows rates carbon is absorbed by land and ocean sinks and other geological processes after we stop emissions. Briefly about 60% 0f CO2 is absorbed in first century, remaining 40% takes up to approx 10,000 years to be absorbed.

It is important to note that the CO2 levels we are currently seeing in the atmosphere are the levels after a significant portion of the emissions that will be absorded in the land and ocean as described in Phase 1 have been absorbed.

So Phase 1 will not be rapidly removing 60 to 85% of the 120 ppm of excess CO2 we currently are measuring (400 ppm - 280 ppm = 120 ppm excess still in the atmosphere). The measured excess CO2 after human activity stops creating new excess CO2 will essentially be the levels for a much longer time, very slowly being reduced by Phase 2 and 3 actions.

Admittedly there will still be some Phase 1 reduction occurring after humans stop creating new excess impacts if the termination is abrupt rather than gradual. But the rate of reduction of the later stages of Phase 1 are also rather slow.

A slightly expanded description could be given, but the detailed descriptions of the 3 phases provided in Box 6.1 say it better than I could paraphrase and they make reference to additional related information.

But the bottom line is that everyone who is benefiting or benefitted from the creation of excess CO2 owes others, particularly future generations of humanity, whatever it costs to reduce the created excess to 350 ppm (those benefiting must pay to eliminate the negative consequences they created - with the bigger beneficiaries paying more to neutralize the impacts of their actions). The inter-generational inequity, and the inequity of benefit in the current generation, of what is being gotten away with is the real matter to be focused on by Responsible Leaders in Politics and Business.

The lack of responsible leadership due to the competitive advantage of getting away with behaving less acceptably and the powerful popularity of misleading marketing are the real problems that climate science has exposed in a big way (or Bigly as one of the biggest trouble-making Winners is often misquoted as saying - he said Big League in a fuzzy way).

Is that right? For constant concentration, net emissions must be near zero? There was a discussion at SkS involving Andy Skuce a few years ago about the effect of suddenly cutting emissions to zero. If I remember correctly, the concentration of atmospheric CO2 begins to fall immediately but the inertia of the climate system ensures that the average global temperature remains roughly constant. Is the word "net" of significance here? I should emphasize that when I say "begins to fall", it does so at a decelerating rate (again, if I remember correctly).

Box 6.1 of Chapter 6 confirms what I remember. After a pulse of CO2 into the atmosphere ceases (emissions = zero) the concentration immediately starts to fall, but at a decelerating rate — down to 40% after about a century, 25% after about 1000 years, and the rest after a further immensely long period.

The implication is that, if humanity reduces its emissions to zero, we'll see a decline in the Keeling curve. Owing to the inertia of the system, this decline might not be fast enough to stop the temperature exceeding two degrees, but that's not what I wanted to know. The foregoing contradicts the assertion by gws @4.

America absented herself from the TPPA and we now are on the way, with the rest of the participants, to a much fairer agreement for the people of the countries involved. The same probably applies to talks on reducing carbon emisions. Leave the obstructionist USA out of it and the rest of us can get on with it. Yes I know they are a major contributor to green house gasses but imagine this. The rest of us agree to Tax and Dividend a la Jim Hansen. Countries that don't put on such a tax have a carbon tariff imposed on them. Once a couple of major countries sign up to this, the rest have to follow. We drag America kicking and screaming into the fold whether they want it or not.

Technically I agree that the exact points 1, 2, 3, 4, 5 presented by gws@4 are not exactly what happens at points 1, 2, 3, 4, and 5 in your initial question @1.

It may be more appropriate to say:

the graph of CO2 ppm in atmosphere will be a humped curve with a maximum at point 4 (hopefully that maximum occurs sooner and lower rather than higher and later).

the graph of the annual human impacts on CO2 in the atmosphere is a curve that is soon to be declining, reaching zero slightly after point 4 in the CO2 ppm curve.

It is also probably more accurate to say that the set of environmental responses to human impacts increasing CO2 in the atmosphere, as presented as Phases 1 through 3 in Box 6.1, begin after any measurable human impact affecting CO2 in the atmosphere occurs. So the rapid atmospheric CO2 draw-downs at the start of Phase 1 have already occurred for the human impacts that were created several decades ago. Even if the termination of human impacts was immediate today only the most recent portion of the 125 ppm surplus CO2 measured today will be reduced at the rapid initial rate of Phase 1 actions.

A more important point is that though the atmospheric CO2 levels will decline after human impacts are ended the damaging changes of ocean acidity will continue to occur. And the 'new' balance point for CO2 in the atmosphere at the distant end of all the adjustments to this damaging spurt of human impacts will likely be above the 280 ppm level. The higher the total spurt of human actions push up CO2 the higher the 'new' balance point will be that atmospheric CO2 drops back down to in the far distant future.

So to be fair to future generations, the current generation is required to remove some of the already created excess CO2. That action is required to minimize the amount of negative impacts and negative challenges for future generations. And that 'sacrifice - no personal benefit' action is primarily the obligation of the already more fortunate portion of the current generation, especially those who benefited most from the burning to date, most especially those who are still trying to benefit even more from the burning of the non-renewable buried hydrocarbons. And that undeniable responsibility for personal sacrifice from the undeserving more fortunate people is a major motivation for the unjustified attacks on climate science.

The complication I see is that the environmental systems are constantly trying to rebalance. So there is a time lag between the changes of the rates of human impacts and the corresponding changes of the Keeling curve.

If human impacts remained constant for an extended, but reasonably short, period of time then the rate of increase of CO2 should also be constant. The complication is that a warmer ocean will likely absorb less CO2. As the constant rate of human impacts goes longer then the rate of CO2 ppm change will increase. Because of the increasing urgency of action to curtail these human impacts, increasing every year that the CO2 level increases, hopefully there will not be a long period of steady significant human impacts.

If human impacts are declining then the rate of increase of CO2 would also be declining.

The constant efforts of the environment to rebalance means that a small but constant amount of human impacts would result in a flat/steady CO2 level in the atmosphere, but the acidification of the oceans would be continuing to happen.

Once human activity impacts are reduced to zero impact on CO2 in the atmosphere the rebalancing/adjustment mechanisms described in Phase 1, 2 and 3 in Box 6.1 of the IPCC report would result in a reduction of CO2 in the atmosphere, but to a level significantly higher than the 280 ppm starting point.

What I have described @14 is also limited to cases where the total human impacts keep CO2 ppm below the level taht would result in significant changes to the feedback mechanisms resulting in an increased amplification of the human impact.

This is the reason to keep the impacts below a 1.5 C impact. Keeping the impacts below 2.0 C also appears to be reaonably safe regarding feedbacks (less safe than 1.5 C), but of course the negative consequences for future generations are significantly higher with a 2.0 C increase than with a 1.5 C increase.

Anyone proposing "acceptability" of total human impacts that are above 2.0 C is being very Irresponsible and very Inconsiderate (putting Private Interests way above the Public Interest).

By inertia I mean the delay following a change while the planet reaches a new equilibrium. So I understand that bit.

As for feedbacks, to me this implies a non-linear response to changes in GHGs.

I also understand that, without humans, there is a continuing interchange of GHGs between land, atmosphere and ocean. Add human emissions, and there will be a rebalancing of this interchange that will require some time.

I think the latter point is where gws @4 gets his "net" emissions.

I conclude that the Keeling curve will remain flat if our emissions are low enough for the planet to accommodate. But in accordance with IPCC Chapter 6, if our emissions really are zero, the Keeling curve will be declining.

The only clarification is that human activities other than burning fossil fuels affect CO2 levels in the atmosphere. And changes of major activities like agriculture and forest management can increase/reduce the amount of CO2 in the atmosphere.

So if the 'net' impact of human activity, not restricted to emissions, is zero then the natural aspects of the environmental system would reduce the levels of CO2 in the atmosphere.

And I understand and agree with your initial point about getting back down to 350 ppm. Human activity to achieve that result is required, not just terminating the negative impacts on CO2 levels before their accumulation would produce a 2.0 C increase of global average surface temperatures. More is required than just changing the games people play to effectively limit what humans are able to get away with so that global 'net-zero carbon' activity is achieved).

The 'charitable/not-for-profit/tax-subsidized' efforts to reduce CO2 to 350 ppm need to start today and be paid for by the people who benefited the most from the past burning of fossil fuels and by any more fortunate person who still tries to personally benefit from the activity. That means the more fortunate need to be getting 'net-zero-benefit' from the burning of fossil fuels and they need to be net-positive for the future of humanity, meaning making personal sacrifice to be net-negative regarding CO2. Any portion of their fortune that came from the past burning of fossil fuels should be expected to be charitably reducing global CO2 impacts (no personal benefit obtained - other than recognition for finally responsibly considerately making amends). Most of them would still be significantly more fortunate than average and they all would become more deserving of being more fortunate than others.

That developing understanding of the required changes fuelled by improved understanding of climate science, particularly the significant required changes by many of the 'currently perceived to be' most fortunate, is a major motivation for the attacks on climate science fuelling efforts for secrecy, excuse-making and manipulation rather than increased honesty, raising awareness and education.

The change of attitude I mentioned is nothing new. It has been an established understanding of Global Leadership for decades. It was formally stated as a part of Kyoto. And is a stated part of the Paris Agreement. It is the parts that trouble-makers accuse of being "Globilist Wealth Grabs" or "Globalist Wealth Transfers".

Global better understanding about how to sustainably improve the future for all of humanity has continued to strengthen in spite of regional short-term variations down from the mean (like global average surface temperature, it is the long term trend that matters).

So it is only a matter of time before the understanding becomes powerful enough to over-rule the pursuers of Private Interests who try to get away with things that are contrary to that understanding, not if it ever will become that powerful.

This is business that has multiple goals, profit plus environment, ethics, employment practices etc.

Attitudes to business ethics and environmental concerns are also slowly changing, from what I have read. Young people are wanting better ethics in business and environmental standards, and it appears more than just teenage idealism. But I think it will be a slow process, especially once mortgage has to be paid! But it absolutely has to change because the alternatives are unthinkable.

Yes, fellows, there are indications that some are changing their attitude. (And I do subscribe to the Listener — and regularly bombard them with "e-mails to the editor".) The question is whether there is enough of a change to render the neanderthals of business and politics impotent. Time will tell.

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